Eric Rasmusen’s Weblog

I went to a class session lecture by Leo Strauss’s co-author Joseph Cropsey back around 1989. It was on Plato’s Protagoras. Cropsey talked as if it were a one-sided conversation, and a lot of what he talked about was Irrational numbers and the Incommensurable. An irrational number is one that can’t be written as a fraction— the square root of 2, or pi, rather than 1/4 or 1/3. Thus, an irrational number is not a ratio, not rational, and is sort of in a different world. I’m not sure if what he said made any sense, but it did make an impression.

Today in the car I was telling Elizabeth and Amelia how two times ten dollars equalled twenty dollars, a thought they liked. I went on to ask what 20 divided by 2 was. Amelia said she didn’t know what “divided by” meant, and that she hadn’t done division yet. I explained. She said that Division was Evil. If Amelia was divided by two, she’d be two dead halves. If we divided two sisters by two, there is just one on each side. It seems they don’t like each other, or are forcibly separated. So Amelia doesn’t like division.

That’s a nice story. Is there some profundity at the bottom of it?

This entry was posted on Tuesday, October 10th, 2006 at 1:11 pm and is filed under Math, Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.